|TLD type||Country code top-level domain|
|Registry||Russian Institute for Public Networks|
|Sponsor||Russian Institute for Public Networks|
|Intended use||Entities from the Soviet Union|
|Actual use||Entities from the post-Soviet states|
|Registered domains||120,294 (May 2013)|
|Structure||Registrations are permitted directly at the second level|
.su was assigned as the country code top-level domain for the Soviet Union on 19 September 1990. Even though the Soviet Union itself was dissolved a mere 14 months later, the .su top-level domain remains in use today. It is administered by the Russian Institute for Public Networks (RIPN, or RosNIIROS in Russian transcription).
After 1989 a set of new internet domains was created in Europe, including .pl (Poland), .cs (Czechoslovakia), .yu (Yugoslavia) and .dd (East Germany). Among them there was also a domain for USSR – .su. Initially (before usage of two-letter domain was a standard) Soviet Union was to receive a .ussr domain. .su domain was invented by the then 19-year-old Finnish student Petri Ojala. On December 26, 1991 the country formally ceased to exist and the individual republics gained independence, which should have caused the domain to be deregistered, as it happened with other domains such as those of East Germany or Czechoslovakia. Until 1993 there was no assigned top-level domain name for Russia. For this reason the country continued to use the Soviet domain. In 1993 the .ru domain was created, which is supposed to eventually replace the .su domain (domains for the republics other than Russia were created at different times in the mid-nineties; however, the domain usage outside the Russian region is slim). The domain was supposed to be withdrawn by ICANN, but it was kept at the request of the Russian government and Internet users.
In 2001, the managers of the domain stated that they will commence accepting new .su registrations, but it is unclear whether this action is compatible with ICANN policies. ICANN has expressed intentions to terminate the .su domain[when?] and IANA states that the domain is being phased out, but lobbyists stated in September 2007 that they had started negotiations with ICANN on retaining the domain. In the first quarter of 2008, .su registrations increased by 45%.
The domain was intended to be used by the Soviet institutions and companies operating in USSR. Currently, despite the formal dissolution of the country and taking over the role of the domain by the domains of republics that gained independence, it is still used. Most of the .su domains are registered in Russia and the United States. According to the RU-CENTER data, there were over 93,500 registered pages with the .su domain (there are over 2.8 million .ru pages). Among the institutions that are still using this domain is the Russian party Nashi, which is connected with the President and Prime Minister of the Russian Federation. In addition, the domain is also used by companies impersonating worldwide concerns, such as Microsoft, Apple or Ford, which have their Russian pages registered in .ru domain. Stockholm University in Sweden also implemented this as SU is their abbreviation, employee emails use the .su extension.  Some organizations that have their roots in the Soviet Union are still using this TLD.
- "nic.ru (Russian ccTLD Registry) domain count". nic.ru.
- Компания "Демос" - первый российский интернет-провайдер. Услуги дата-центра, офисная телефония, Интернет, хостинг - Компания Демос (in Russian), retrieved January 12, 2010
- Marcin Kryska. "Domena internetowa SU" (in Polish). Retrieved June 11, 2012.
- "Юбилей Рунета: 10 лет назад финн Петри Ойала зарегистрировал домен .su" (in Russian). Retrieved January 12, 2010.
- .su Domain Delegation Data IANA
- Kilner, James (19 September 2007). "USSR still alive on Internet and won't go quietly". Reuters. Archived from the original on 13 December 2007. Retrieved 5 December 2007.
- Back in the USSR: Soviet Internet domain name resists death, Mansur Mirovalev, writing for Associated Press, 18 April 2008
- "Domena .su wciąż używana, chociaż ZSRR już nie ma" (in Polish). Retrieved January 12, 2010.
- "RU TLD: Registration and Delegation Statistics". Retrieved May 11, 2010.
- Nashi. "Молодёжное демократическое антифашистское движение НАШИ / Главная" (in Russian). Retrieved January 12, 2010.
- Radziecka domena nie chce odejść do lamusa (in Polish), retrieved January 12, 2010
- "Tons of Hackers are Hanging out in old Soviet Cyberspace". Gizmodo.